Up unitl the 1980s, cabooses served a vital purpose at the end of the train: from the viewing area atop the roof (called the "cupola,") a member of the train's crew could see along the length of the entire train, so that he or she can be forewarned of problems or adverse conditions that might require the train to stop.
Before the turn of the century, some of the most important people working on a train and stationed in the caboose were the brakemen. Until the invention and widespread application of George Westinghouse's airbrake in the later 19th century, each passenger or freight car had its own brake, which had to be set individually on each car by means of turning a large wheel. To stop the train in an emergency, the engineer would ram his locomotive in reverse, while the two or three brakemen on the train scrambled across the car roofs from car to car hand-setting the brakes. The inability to make rapid stops led to many accidents. Every second's delay could mean the difference between stopping the train in time or suffering an accident or derailment. There was always a crew member on watch in the caboose looking out the cupola for any danger that might lie ahead of the train. The development of air brakes, which allowed the engineer to stop every car simultaneously, profoundly affected railroad safety.